1. Field of the Invention
The present invention relates to a shutter device.
2. Description of the Related Art
In a method discussed in Japanese Patent No. 3542192, in a focal plane shutter, a blade drive lever is moved against a spring force from a drive spring with a pivot operation of a charge lever. In order to reduce the friction between the charge lever and the blade drive lever, a roller, which is supported by the blade drive lever, is caused to come into contact with the charge lever.
In the focal plane shutter discussed in Japanese Patent No. 3542192, a surface of a shutter base plate functions to prevent falling off of the roller. However, lubricating oil, which is applied to a rotation shaft of the roller to enable a smooth rotation of the roller, may spread onto the surface of the shutter base plate. The lubricating oil that has spread on the surface of the shutter base plate may become a resistance to the travel of a pivot operation by the blade drive lever. Accordingly, in this case, the pivot speed of the blade drive lever may vary. As a result, the accuracy of travel of the shutter blade may degrade.
Furthermore, the roller may contact or separate from the shutter base plate if the orientation of the focal plane shutter has varied and the gravity acting on the roller has varied. As a result, the pivot speed of the blade drive lever may vary, which may result in degrading the accuracy of travel of the shutter blade.